Granted, not all the bridges in my experience were on the grand scale. There were some that were older and smaller. In fact, there was a whole range, from the simple farm road bridges that crossed streams where my parents would stop to net for bait before going fishing, to the crumbling aged bridges that spanned the Des Plaines and Fox Rivers as we canoed underneath and admired the elegant sculptural details built decades ago.
Bridges sometimes harbor, not trolls, but other interesting animals that live beneath their shelter. Here in Austin, the Congress Street Bridge is famous for its summer maternity colony of Mexican free-tail bats. One and a half million mother bats huddle under the modestly sized bridge in order to give birth each year. Birds such as swallows and pigeons frequently roost under bridges as well. Smaller bridges provide places to glimpse mud-nest building wasps up close and sometimes there are spiders in abundance. Some things do not live, but grow under bridges: calcium deposits formed by dripping water. These soda straw like formations are very similar to those found in caves and I've seen a few up to several inches long.
Some bridges had names, such as Warner's Bridge, which crossed the Kankakee River in the state park of the same name. My family frequently fished in the shade of the large concrete arches, played around the pilings, and looked for fossils in the gravel dumped along the shore to control erosion beneath the bridge. During one particularly cold winter, the ice piled up so high that my father wrote our names under the top of one span. From the ground, it was just barely visible. Since there were convenient places to park, play, fish and make lunch right under Warner's Bridge, we spent a lot of time there. The river was rather wide and had many gravel bars and islands, and we knew the topography that lay invisible beneath the often muddy waters. It amused me to watch the occasional motorboat sputtering upstream hit a gravel bar, making the propeller bounce up out of the water. The exclamations of displeasure as the boat's occupants assessed the damage were probably one of my earliest lessons in the more colorful uses of the English language.
One bridge in our area was bigger than any other: it crossed the Des Plaines River, Calumet Sag Channel, Chicago Sanitary and Ship Canal, and the old Illinois and Michigan Canal. I always assumed that the Sag Bridge was named for the nearby Saganashkee Slough, a moniker probably of Native American origin. The main attraction in the area under the bridge was an old abandoned limestone quarry that had become several splendid ponds once the mining was done. Unlike the murky waters of nearby rivers, these quarries were clear. Instead of muddy banks, there were rocks and even huge slabs of limestone that were as flat as concrete sidewalks. We netted for fish, watched 3-foot long carp spawn, and caught baby water snakes along the shores. Although we often waded in the water, we rarely swam there. Stories of large abandoned mining equipment in the depths were just creepy enough to keep us near the few banks that were not steep drop-offs. I'm sure that if summers in Illinois were as hot as they are here in Texas, our fears would have been quickly overcome, as the waters were cool and refreshing.
Besides the quarries, there were gravelly fields and small wooded areas with rich black soil beneath the bridge. Flocks of swallows often swooped here and there, going to and from their nests on their quests for insects. We picked tiny succulent wild strawberries that thrived in the poor soil, as well as the occasional giant puffballs that unpredictably appeared. Foxes, snakes, and woodchucks were sometimes glimpsed. The traffic soared so high over our heads that there was little noise from it, so it was easy to forget that other world, so different from the one far below. The funny thing was that when we drove over the bridge, it was easy to forget in the other direction as well.
Since I've lived in Austin, the tall Mopac (Route 1) highway bridge over Barton Creek was built. I followed the progress of the construction, from the first concrete monoliths to the completed bridge, which I walked on before it was opened to traffic. In spite of all the disruption of the terrain beneath the bridge, it has continued to be a fascinating place to hike.
On a recent Florida vacation with Larry and my mother, Ev, we hiked a trail in the Ocala National Forest that ended under one of those incredibly high bridges. This one did not have much of interest below, as the vegetation appeared to be regularly mowed, but the feeling of awe at the massive columns and non-human proportioned length of the spans reminded me once more of how small one can feel under a bridge.